Difference between ALTER and UPDATE Command in SQL (2024)

FAQs

Difference between ALTER and UPDATE Command in SQL? ›

The main difference between the two is that the ALTER command adds, deletes, modifies, renames the attributes of the relation, and the UPDATE command modifies the values of the records in the relations. ALTER command is attribute or column specific, and the UPDATE command is attribute-value-specific.

ALTER Command is used to add, delete, modify the attributes of the relations (tables) in the database. UPDATE Command is used to update existing records in a database. ALTER Command by default initializes values of all the tuple as NULL. UPDATE Command sets specified values in the command to the tuples.

MODIFY - Will update the table, if the data already exists, if NOT inserts new rows. UPDATE - Will update the table, errors out if the data is not found. In case of MODIFY the sy-subrc is always 0 so you would't know whether the data is actually updated or not.

In summary, use INSERT to add new records, UPDATE to modify existing records, and ALTER to modify the structure of a table.

What is an ALTER Statement in SQL? The ALTER TABLE can be used in order to add, drop, delete, or modify the columns in an already existing table. This statement can also be used to add or drop multiple constraints on an already existing table.

"Drop" in SQL refers to the removal of a table or database from a server. "Truncate" is a SQL command that removes all rows from a table but keeps the table's structure intact.

All changes made by the following statements executed during the unit of work are committed: ALTER, COMMENT, CREATE, DROP, GRANT, LOCK TABLE, REVOKE, SET INTEGRITY, and the data change statements (INSERT, DELETE, MERGE, UPDATE), including those nested in a query.

SQL UPDATE Statement is used to update data in an existing table in the database. The UPDATE statement can update single or multiple columns using the SET clause. The WHERE clause is used to specify the condition for selecting the rows to be updated.

DROP and DELETE statements in the SQL are used to remove the data, but they operate at different levels. DROP command in SQL deletes entire database objects and their data, whereas the DELETE command removes specific rows from the table (specified by the WHERE clause).

To rename TEMPORARY tables, RENAME TABLE does not work. Use ALTER TABLE instead. RENAME TABLE works for views, except that views cannot be renamed into a different database. Any privileges granted specifically for a renamed table or view are not migrated to the new name.

What is the purpose of ALTER in SQL? ›

The ALTER TABLE statement is used to add, delete, or modify columns in an existing table. The ALTER TABLE statement is also used to add and drop various constraints on an existing table.

You can't use UPDATE instead of INSERT, but the UPSERT statement is a good alternative. With the UPSERT statement, the database updates records where they are available and inserts them in the table if the record does not exist. INSERT is faster than an UPDATE statement provided a database is properly optimized.

The syntax would be as below: DROP TABLE IF EXISTS table_name; This clause verifies the existence of the table in question in the current database. If the table is found, the command proceeds to drop it.

ALTER command will perform all the actions in the table at a structural level. UPDATE command will perform all the actions in the table at the data level. It is used for adding, deleting, and modifying attributes of the table in the database. It is used for updating the data (records) in the existing table.

TRUNCATE TABLE command in SQL is used to remove all the records from the table or specified partitions of a table. Once the TRUNCATE command is used, you can't recover the data even using ROLLBACK. It is similar to the DELETE command in SQL without a WHERE clause.

Drop table removes the table along with its content. Alter changes its structure depending on the parameter you give to the command: you can add, remove, rename colums, add constraints etc. Alter keeps the table content (of course removing a column will remove that column's data from the content).

ALTER vs UPDATE command📋

ALTER Command changes the definition of the table. UPDATE command operates on the data level. This command is used to add, delete, and modify the attributes of the tables in a database. It updates the existing records in a database.

What is the difference between updates and upgrades — and why are they important? Software updates (patches) modify an existing program. Upgrades replace a program with its next major version. Running current software improves the stability and security of your systems.

change implies making either an essential difference often amounting to a loss of original identity or a substitution of one thing for another. alter implies a difference in some particular respect without suggesting loss of identity.

ALTER is used for changing table general properties such as columns, data types, names of columns, etc. For example you want to change the data type of column "name" from text to catch at. UPDATE is used to change values of data in already existing columns in a table.